It's hard to tell without knowledge on both Macs and how you installed CS4 on both of them. Are both Macs intel? Did you do a clean install from a disc? Download? Did you try trashing the prefs on open? http://forums.adobe.com/thread/526990

And take a look at Adobe Forums: InDesign CS5.5 Not Responding where you'l find directions for creating a hang report and then forcing a crash and generating that report. We can often pinpoint the problem if we have that information.